Each gravite weapon starts at 20% charge. A fully charged gravite weapon will last for ten hours of combined combat. The timer will run out more quickly if multiple foes are attacking you at once. Once the charge has been used up, it can be recharged, for a fee, by the rewards trader. To do so, right-click on him, and select 'Recharge', while having the depleted weapon in your inventory.

You can choose to pay coins or a combination of coins and dungeoneering tokens. Repairing a gravite weapon at 0% charge will cost you either 1,000,000 gp or 100,000 gp and 6,500 tokens.